Expansible intravertebral implant system with posterior pedicle fixation

ABSTRACT

The present invention relates to an expansible intravertebral implant system comprising an intravertebral implant ( 1 ) with an expandable anterior part ( 11 ), which is expansible in a vertebral body, and a posterior part; and a pedicle fixation ( 2 ) having at least one hollow portion for receiving the posterior part. The present invention also relates to said expansible intravertebral implant system additionally comprising a posterior element ( 3 ), arranged partially outside the vertebra and rigidly connected to the pedicle fixation ( 2 ), for serving as an anchoring point for at least one intravertebral rod or at least one system of artificial ligaments.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national stage application of InternationalApplication No. PCT/FR2014/053549, which was filed on Dec. 23, 2014, andentitled “Expansible Intravertebral Implant System with PosteriorPedicle Fixation,” which in turn claims priority to French PatentApplication No. 1363467, filed Dec. 23, 2013, of the same title. Theentire content of the aforementioned applications are herein expresslyincorporated by reference.

FIELD OF THE INVENTION

The present invention relates to an expandable intravertebral implantsystem with posterior pedicle fixation. More particularly, the presentinvention relates to an expandable intravertebral implant systemoffering enhanced vertebral anchoring by adding a pedicle dowel firmlyanchored in a vertebral pedicle.

STATE OF THE RELATED ART

Several vertebroplasty techniques are known for performing vertebralcorrection enabling a vertebra deformed following bone compression, forexample due to osteoporosis or an injury, to return to the initial shapeor morphology thereof.

For example, the kyphoplasty technique is known, consisting ofintroducing an inflatable balloon into a vertebra, then sending apressurised fluid into the balloon placed in the vertebra in order toforce the cortical envelope of the vertebra, and particularly the lowerand upper vertebral plates to return to a corrected shape under theeffect of the pressure. Once the cortical bone envelope has beencorrected, the balloon is then deflated, and removed from the vertebra,in order to be able to inject therein a bone cement intended to give thecorrected vertebra a stable mechanical strength over time.

Through the international patent application WO2005/120400 inparticular, an expandable implant is known, comprising a first and asecond opposite plates, suitable for respectively forming a first and asecond bearing surfaces in a vertebral body; these two bearing surfacesbeing called upon to separate from one another along a predefinedexpansion plane. The expandable implant is positioned in the vertebralbody, and the plates are deployed along an expansion plane whichcorresponds to the bone correction plane sought. A bone cement is theninjected in order to stabilise the bone correction.

The bone cement may be injected with a relatively low pressure by meansof the implant which remains in position in the vertebral body.

In the case of the most severe injuries, the use of the methods citedabove may prove to be insufficient. The repair of vertebral fractures,and particularly vertebral fractures induced by compression is thenpreferentially performed by means of screws inserted into the pediclesof the over- and underlying vertebrae of the compressed vertebra, thesescrews being associated with posterior rods, thus mechanicallyconnecting the two over- and underlying vertebrae to enable vertebralconsolidation. Pedicle screws are well-known in the prior art. Screwssuch as those described in the U.S. Pat. No. 5,209,753 are particularlyknown.

The drawback of this technique lies in the fusion of two vertebral jointlevels caused by the fixation of the posterior rods connecting the over-and underlying vertebrae. Furthermore, these methods do not alwaysenable bone correction of the compressed vertebra but merely thestabilisation of three adjacent vertebrae and thus the locking of twojoint levels. The surgical act associated with this procedure isfurthermore very invasive and requires access to at least two vertebrae.

In order to remedy these drawbacks, it appears to be necessary toprovide a device enabling the repair of vertebral fractures, andparticularly severe vertebral fractures caused by compression,preventing fusion and enabling consolidation, at the pedicle, of anexpandable intravertebral implant situated in the vertebral body.

As such, the aim of the invention is to associate with an expandableintravertebral implant, positioned in a vertebral body, a pediclefixation (for example dowel or sleeve), intended to be anchored in thepedicle. This pedicle fixation ensures high-quality support andanchoring of the bone. Indeed, while the vertebral body consists ofspongy bone, having a high porosity of 30 to 90%, the pedicle consistsof cortical bone, having a porosity of 5 to 30%, thus offering strongmechanical support for the intravertebral implant and making it possibleto reconstruct vertebral fractures, and particularly vertebral fracturescaused by compression, even the most severe.

Extendable bone implant systems comprising an additional anchoring inthe pedicle bone are known, such as for example the systems described inthe patent applications EP 2 074 956 and US 2009/005821. However, thesesystems describe an expandable member rigidly connected to said pediclefixation, for example by screwing both parts. For this reason, thedirection of expansion of the expandable member and the positioning ofthe member in the vertebral body are directly dependent on the positionof the pedicle fixation.

The invention has the advantage of enabling the deployment of theexpandable intravertebral implant independently, along at least onedegree of freedom, of the position of the pedicle fixation. The implantsystem also makes it possible to secure (i.e. lock all the degrees offreedom) said extendable intravertebral implant with respect to thepedicle fixation, when the implant system is positioned in extension inthe vertebra.

Advantageously, a posterior element acting as a connection system isassociated with the pedicle fixation element, making it possible toadjoin to the expandable intravertebral implant means completing thebone correction, for example using posterior rods or other systemintended to stabilise the fracture site further.

As such, the present invention ensures vertebral correction using amodular expandable intravertebral implant system with posterior pediclefixation.

SUMMARY

The invention thus relates to an expandable intravertebral implantsystem comprising an intravertebral implant comprising an expandableanterior part in a vertebral body and a posterior part; and a pediclefixation having at least one hollow portion for receiving the posteriorpart of the intravertebral implant.

According to one embodiment, the pedicle fixation comprises an externalthread ensuring the anchoring of said pedicle fixation in a vertebralpedicle.

According to one embodiment, the pedicle fixation comprises a hollowposterior inner portion and a hollow anterior inner portion wherein theposterior part of the intravertebral implant can move along at least onedegree of freedom.

According to one embodiment, the pedicle fixation comprises a main axisand the posterior part of the intravertebral implant can move intranslation and in rotation, along the main axis of the pediclefixation, in the anterior inner portion of the pedicle fixation; in sucha way that the direction of expansion of the anterior part of theanterior part of the intravertebral implant is independent from theposition of the pedicle fixation in the vertebral pedicle.

According to one embodiment, the anterior part of the intravertebralimplant comprises a first and a second plates, suitable for respectivelyforming a first and a second bearing surfaces in a vertebral body; thesetwo surfaces being suitable for being separated from one another along apredefined expansion plane.

According to one embodiment, the anterior inner portion comprises atleast one groove on the inner surface thereof.

According to one embodiment, a posterior portion of the posterior partof the intravertebral implant comprises a cylindrical recess and atleast one securing means suitable for locking in rotation and intranslation the relative movements between the intravertebral implantand the pedicle fixation.

According to one embodiment, the securing means comprises at least onethrough hole, passing through the posterior portion and a peripheralchamber to the surface of the posterior portion in fluid communicationwith the at least one through hole.

According to one embodiment, the securing means comprises at least twoslots extending axially along the posterior portion, an internal threadand a flared posterior end; suitable for engaging with a conicalexpansion cap.

According to one embodiment, the posterior element is secured to thepedicle fixation by means of a threaded rod screwed into an internalthread of the posterior inner portion.

According to one embodiment, the posterior element comprises a posteriorportion suitable for assembly with additional posterior fixationelements such as rods or artificial ligaments.

BRIEF DESCRIPTION OF THE FIGURES

Further specific features and advantages will emerge clearly from thedescription hereinafter, by way of indication and in no way limiting,with reference to the appended drawings, wherein:

FIG. 1 is an exploded view of the implant system according to oneembodiment of the present invention.

FIG. 2 is a side view of the intravertebral implant according to oneembodiment of the present invention.

FIG. 3A is a side view of the pedicle fixation according to oneembodiment of the present invention.

FIG. 3B is a sectional view of the pedicle fixation according to oneembodiment of the present invention.

FIG. 4 is a perspective view of the posterior element according to oneembodiment of the present invention.

FIG. 5 is a side view of the implant system according to one embodimentof the present invention, mounted on an instrument suitable for theinsertion of the implant system.

FIG. 6A is a side view of the implant system, according to oneembodiment of the present invention, placed in a vertebra; said vertebrabeing represented as transparent, visible merely by the outlinesthereof.

FIG. 6B is a top view of the implant system, according to one embodimentof the present invention, placed in a vertebra; said vertebra beingrepresented as transparent, visible merely by the outlines thereof.

FIG. 7A is a sectional view of the implant system according to oneembodiment of the present invention, prior to expansion of the anteriorpart of the implant.

FIG. 7B is a sectional view of the implant system according to oneembodiment of the present invention, after expansion of the anteriorpart of the implant.

FIG. 8A is a sectional view of the implant system, after expansion ofthe anterior part of the implant illustrating the means for securing thepedicle fixation to the intravertebral implant according to oneembodiment of the present invention.

FIG. 8B is a perspective view of the intravertebral implant, afterexpansion of the anterior part of the implant illustrating the means forsecuring the pedicle fixation to the implant according to one embodimentof the present invention.

FIG. 8C is a perspective view of the pedicle fixation particularlyillustrating the anterior inner portion according to one embodiment ofthe present invention.

FIG. 9A is a sectional view of the implant system, after expansion ofthe anterior part of the implant illustrating the means for securing thepedicle fixation to the intravertebral implant according to oneembodiment of the present invention.

FIG. 9B is a perspective view of the implant system, after expansion ofthe anterior part of the implant illustrating the means for securing thepedicle fixation to the intravertebral implant according to oneembodiment of the present invention.

FIG. 10A is a side view of the implant system according to oneembodiment of the present invention placed in a vertebra; said vertebrabeing represented as transparent, visible merely by the outlinesthereof.

FIG. 10B is a sectional view of the implant system according to oneembodiment of the present invention placed in a vertebra; said vertebrabeing represented as transparent, visible merely by the outlinesthereof.

The drawings in the figures are not to scale. Obviously, the scope ofthe invention is not restricted to examples of embodiments morespecifically described and represented with reference to the appendedfigures; on the contrary, it includes any alternative embodiments.

REFERENCES

-   1 Anterior part of the intravertebral implant,-   11 Posterior part of the intravertebral implant,-   121 Shoulder,-   122 Cylindrical recess,-   123 Chamber,-   124 Through hole,-   125 Slot,-   126 Internal thread,-   127 Flared posterior end,-   128 Posterior portion of the posterior part of the intravertebral    implant,-   13 Central traction tube,-   131 Through hole,-   2 Pedicle fixation, particularly pedicle dowel,-   21 External thread,-   22 Posterior inner portion,-   221 Internal thread,-   23 Anterior inner portion,-   231 Groove,-   24 Means for rotating the pedicle fixation—Notch,-   25 Entry chamfer,-   3 Posterior element,-   31 Anterior portion,-   311 External thread,-   32 Posterior portion,-   33 Bearing surface,-   4 Vertebra,-   5 Insertion instrument,-   51 Cannula rotatably connected to the pedicle fixation,-   52 Expansion tube,-   6 Conical expansion cap.

DETAILED DESCRIPTION

The present invention relates to an expandable intravertebral implantsystem with posterior pedicle fixation.

According to a first embodiment, the implant system comprises anintravertebral implant associated with a pedicle fixation ensuringadditional anchoring at the vertebral pedicle.

According to a second embodiment, as represent in FIG. 1, the implantsystem comprises an intravertebral implant 1 associated with a pediclefixation 2 and with a posterior element 3 suitable for connecting,posterior to the vertebra, any device intended to stabilise, reinforceor repair the vertebral fracture, particularly the vertebral fracturecaused by compression.

Intravertebral Implant

As represented in FIG. 2, the intravertebral implant 1 according to thepresent invention comprises an anterior part 11 and a posterior part 12.

According to one embodiment, the anterior part 11 corresponds to adeformable and expandable intravertebral implant 1 such as theSpineJack® implant marketed by the company VEXIM, known to those skilledin the art and also described in the patent application EP 1 778 136,incorporated herein by reference. It is specified that those skilled inthe art, on reading said patent application, would readily find thefeatures required for the embodiment of the present invention. Inparticular, the anterior part 11 of the intravertebral implant 1 of thepresent invention consists of an expandable part enabling bonecorrection and comprising:

-   -   a predetermined single expansion plane, intrinsic to said        anterior part 11,    -   a first and a second opposite plates, suitable for respectively        forming a first and a second bearing surfaces in a vertebral        body; these two bearing surfaces being intended to separate from        one another along said expansion plane upon expansion of the        implant,    -   a first and a second supports for each of said first and second        plates, situated respectively thereunder, and    -   means for setting a predetermined expansion value, including a        veil of material arranged between said support and a        corresponding plate, said veil having a predetermined thickness        making it possible to monitor the expansion of the implant.        According to one embodiment, said anterior part 11 also        comprises a central traction tube 13 suitable for controlling        the expansion of the first and second plates. According to one        alternative embodiment, the anterior part 11 of the        intravertebral implant 1 corresponds to any intravertebral        implant known to those skilled in the art which is deformable,        expandable and suitable for remaining in the vertebral body        after expansion.

According to one embodiment, as represented in FIGS. 7A-B, 8A-B, 9A-Band 10A-B, the central traction tube 13 is hollow and comprises at leastone through hole 131 suitable for injecting a filling material into thevertebra 4, such as bone cement, after the expansion of the first andsecond plates. According to one embodiment, the central traction tube 13comprises at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 through holes 131.According to one embodiment, the through hole(s) 131 pass(es) radiallythrough the central traction tube 13 so as to enable fluid communicationbetween the inner conduit and the outer surface. According to oneembodiment, the central traction tube 13 comprises a plurality ofthrough holes 131 regularly distributed on the surface thereof.According to one embodiment, the at least one through hole 131 issituated between the two plates so as to be in fluid communication withthe inside of the vertebra after the expansion of the implant and theseparation of the two plates. Advantageously, the injection of a fillingmaterial into the vertebra 4 makes it possible to hold the anterior part11 of the implant 1 in position in the vertebral body after expansion.According to one embodiment, the filling material is a biocompatiblebone cement, for example an ionic cement, a phosphocalcium cement, anacrylic cement or a composite thereof, or a resin. According to oneembodiment, the filling material solidifies after injection.Advantageously, the solidification of the filling material makes itpossible to consolidate the vertebra 4 and reinforce the strength of theimplantation of the implant system in the vertebra 4.

According to one embodiment, the posterior part 12 is a hollowcylindrical body connected, at the anterior end thereof, to theposterior end of the anterior part 11 by a shoulder 121. Said posteriorpart 12 comprises a cylindrical recess 122 through which a centraltraction tube 13, initially situated in the anterior part 11, can slide.By pulling on the central traction tube 13, the central traction tube 13slides in the cylindrical recess 122 of the posterior part 12 and theanterior and posterior ends of the anterior part 11 move closer, causingthe expansion of the first and second plates of the anterior part 11 ofthe intravertebral implant 1. The central traction tube 13 is suitablefor controlling the deployment of the expandable deformable anteriorpart 11. Once the traction tube 13 has been pulled inside the recess122, the tube can no longer return to the initial position thereof,which holds the expansion of the anterior part 11, pending the injectionof bone cement or substitute.

According to one embodiment illustrated in particular by FIG. 8B, theposterior part 12 of the intravertebral implant 1 comprises acylindrical recess 122 and at least one through hole 124.Advantageously, the at least one through hole is situated in theposterior portion 128 of the posterior part 12. According to oneembodiment, the posterior portion 128 corresponds to the portion of theposterior part of the intravertebral implant 12 which remainspermanently inside the anterior inner portion 23. According to oneembodiment, the cylindrical recess 122 passes through the entireposterior part of the implant 12. According to one embodiment, theposterior part of the intravertebral implant 12, and particularly theposterior portion 128 further comprises a portion with a reduced outerdiameter thus defining a peripheral chamber 123. According to oneembodiment, the at least one through hole 124 passes through theposterior part of the implant 12 from the cylindrical recess 122 to theperipheral chamber 123. According to one embodiment, the posterior part12 of the implant, and particularly the posterior portion 128 thereofcomprises at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 through holes 124.According to one embodiment, the through holes 124 are regularlydistributed on the posterior portion 128.

According to one embodiment illustrated by FIG. 9B, the posterior partof the intravertebral implant 12 comprises a cylindrical recess 122 andat least one slot 125 through the posterior part 12 and extendingaxially. Advantageously, the at least one slot 125 is situated in theposterior portion 128 of the posterior part 12. According to oneembodiment, the posterior portion 128 corresponds to the portion of theposterior part of the intravertebral implant 12 which remainspermanently inside the anterior inner portion 23. According to oneembodiment, the cylindrical recess 122 passes through the entireposterior part of the implant 12. According to one embodiment, theposterior part of the intravertebral implant 12, and particularly theposterior portion 128 further comprises an internal thread 126 situatedon the inner surface of the cylindrical recess 122. According to oneembodiment, the posterior part of the intravertebral implant 12, andparticularly the posterior portion 128 further comprises a flaredposterior end 127 suitable for engaging with a conical expansion cap 6.According to one embodiment, the posterior part 12 comprises at least 1,2, 3, 4, 5, 6, 7, 8, 9, 10 slots 125. According to one embodiment, theslot 125 extends along all or part of the posterior portion 128.According to one embodiment, the thread 126 extends along all or part ofthe posterior portion 128.

According to one embodiment, the expansion of the intervertebral implant1 is not due to the injection of a product into the posterior part ofthe implant 1. However, the injection of a filling material can make itpossible to stabilise the implant once in the expansion positionthereof. According to one embodiment, the intervertebral implant 1 doesnot comprise a pouch intended to be filled with a product (e.g. afilling material) so as to enable the expansion of the pouch. Accordingto one embodiment, the injection of a filling material through theanterior part 11 alone, does not allow the expansion of theintravertebral implant 1.

According to one embodiment, the posterior part 12 of the intravertebralimplant 1 does not comprise an outer thread intended to be screwed withthe pedicle fixation 2.

Pedicle Fixation

As represented in FIG. 3A, the pedicle fixation 2 according to thepresent invention comprises at least one thread 21. According to oneembodiment, the pedicle fixation 2 comprises a thread 21 on the outersurface of the pedicle fixation 2. Said external thread 21 is suitablefor providing bone anchoring in the pedicle. The anchoring of thepedicle fixation 2 in a vertebral pedicle offers additional mechanicalsupport to the intravertebral implant 1, and particularly to theexpandable anterior part 11 of said implant 1. The insertion of thepedicle fixation 2 in the bone tissue is facilitated by a chamfer 25situated at the anterior end of the pedicle fixation 2. According to oneembodiment, the outer surface of the pedicle fixation 2 has no textureother than that induced by an external thread, such as for example ameshed, striated or mottled structure. As represented in FIG. 3B, thepedicle fixation 2 is a hollow cylindrical pedicle dowel or sleevecomprising a posterior inner portion 22 and an anterior inner portion23. According to one embodiment, the pedicle fixation 2 is not a solidpedicle screw comprising a hollow inner partial portion. According toone embodiment, the pedicle fixation 2 is hollow along the entire lengththereof. According to one embodiment, the posterior 22 and anterior 23inner portions do not have the same surface condition.

According to one embodiment, the posterior inner portion 22 comprises aninternal thread 221 or any other means within the scope of those skilledin the art for connecting the fixation 2 to a posterior element 3.

According to one embodiment, the anterior inner portion 23 comprises abore defining a hollow portion for receiving the posterior part 12 ofthe intravertebral implant 1. According to one embodiment, the surfaceof the anterior inner portion 23 is smooth. According to one embodiment,the surface of the anterior inner portion 23 is not threaded. Accordingto one embodiment, the intravertebral implant 1, and particularly theposterior part 12, does not pass through the entire hollow pediclefixation 2. According to one embodiment, the posterior part 12 of theintravertebral implant 1 is intended to be inserted inside the anteriorinner portion 23. According to one embodiment, the posterior part 12acts as a guide for the pedicle fixation 2. The shoulder 121 thus actsas a guiding stop for the fixation 2. According to one embodiment, theposterior part 12 of the intravertebral implant 1 can move along atleast one degree of freedom, preferentially 2 degrees of freedom in theanterior inner portion 23 of the pedicle fixation 2. According to oneembodiment, the posterior part 12 of the intravertebral implant 1 issliding in the anterior inner portion 23. According to one embodiment,the mechanical link between the posterior part 12 and the anterior innerportion 23 is a sliding pivot link. According to one embodiment, thepedicle fixation 2, particularly the pedicle dowel, defines a main axis.According to this embodiment, the posterior part 12 of theintravertebral implant 1 can move in rotation and in translation alongsaid main axis in the anterior inner portion 23 of the pedicle fixation2.

Advantageously, the anterior portion 23 enables the expansion of theintervertebral implant 1 independently of the anchoring of the pediclefixation 2 in the vertebral pedicle. Indeed, the degree of freedom intranslation along the main axis of the pedicle fixation 2 makes itpossible not to constrain the positioning (i.e. the advance due todeployment) of the intervertebral implant 1 in the vertebral body.Furthermore, the degree of freedom in rotation about the main axis ofthe pedicle fixation 2 makes it possible not to constrain the directionof expansion of the intervertebral implant 1. As such, theintervertebral implant 1, when deployed, adapts the deployment positionthereof according to the medium wherein it is deployed (i.e. thevertebral body).

According to one embodiment, the anterior inner portion 23 does notcomprise an outer thread. According to one embodiment, the anteriorinner portion 23 and the intervertebral implant 1 are not screwed.

According to one embodiment, the anterior inner portion 23 furthercomprises at least one groove 231, as represented in FIG. 8C. Accordingto one embodiment, the anterior inner portion 23 comprises at least oneaxial groove (i.e. a groove parallel with the z axis). According to oneembodiment, the anterior inner portion 23 comprises at least onetransverse groove (i.e. perpendicular to the z axis). According to oneembodiment, the anterior inner portion 23 comprises at least one obliquegroove 231.

According to one embodiment, the anterior inner portion 23 comprises atleast one axial and/or transverse and/or oblique groove 231. Accordingto one embodiment, the at least one groove 231 comprises a non-constantcross-section. According to one embodiment, the anterior inner portion23 comprises at least 2, 3, 4, 5, 6, 7, 8, 9, 10 grooves 231. Accordingto one embodiment, the grooves are regularly distributed on the innersurface of the anterior portion 12. According to one embodiment, thepedicle fixation 2 comprises at least one notch 24, or any other meanswithin the scope of those skilled in the art, suitable for rotating thepedicle fixation 2, using an insertion instrument 5.

Posterior Element

As represented in FIG. 4, the posterior element 3 according to thepresent invention comprises an anterior portion 31 consisting of a rod,preferably a threaded rod 311 engaging with the internal thread 221 ofthe pedicle fixation 2, thus enabling the fixation of the posteriorelement 3 to the pedicle fixation 2. The posterior element 3 alsocomprises a posterior portion 32, external to the vertebra 4, thegeometry whereof makes it possible to carry out assembly functions withcomplementary posterior fixation elements known to those skilled in theart such as rods or artificial ligaments. Any other assemblyconfiguration with other systems known to those skilled in the art canbe envisaged. The posterior element 3 also comprises a bearing surface33 against bone tissue or against the posterior portion of the pediclefixation 2, according to the choice made by the operator and/or thepenetration of the pedicle fixation 2 in the pedicle bone.

Operation

After the creation of an approach and the boring of the vertebralpedicle, the implant system comprising the pedicle fixation 2 and thevertebral implant 1 wherein the posterior part 12 is inserted in theanterior inner portion 23 of the pedicle fixation 2 is inserted, andthen screwed, into the pedicle using an insertion instrument 5, asrepresented in FIG. 5. Said insertion instrument 5 comprises a workingcannula 51 rotatably secured (i.e. connected) to the pedicle fixation 2by means of the notches 24 for screwing the pedicle fixation 2 in thepedicle. Said insertion instrument 5 also comprises an expansion tube 52situated along the main axis of the insertion instrument 5 and it isconfigured to traverse at least the length of the posterior innerportion 22. The expansion tube 52 is secured (i.e. connected) to theposterior part 12 of the intravertebral implant 1, and particularlysecured to the central traction tube 13 of the intravertebral implant 1.The insertion depth of the implant system is controlled by the screwingof the external thread 21 of the pedicle fixation 2 in the bone tissue,so as to position the intravertebral implant 1 optimally in thevertebral body. The positioning of the intravertebral implant 1 in axialrotation is controlled by the operator independently of the insertion ofthe pedicle fixation 2, using the tube 52 so as to retain an expansionplane, for example a cranio-caudal expansion plane of the intravertebralimplant 1 regardless of the screwing angle obtained during the insertionof the pedicle fixation 2. As represented in FIGS. 6A, 6B, 10A and 10B,the intravertebral implant system according to the present invention isinserted through a vertebral pedicle, the intravertebral implant 1 thenbeing situated in the vertebral body and the pedicle fixation 2 beinganchored in the pedicle.

According to one embodiment, after insertion of the implant system, thepedicle fixation 2 is securely fixed in the pedicle and theintravertebral implant 1 is partially secured to the pedicle fixation 2by the cylindrical posterior part 12 thereof. Indeed, the cylindricalposterior part 12 is inserted into the anterior inner portion 23 thuslocking the rotation movements about the y and x axes and locking thetranslations along said x and y axes. For this reason, these lockeddegrees of freedom ensure partial securing between the cylindricalposterior part 12 inserted into the anterior inner portion 23. The termsecuring denotes the locking of all the degrees of freedom between thepedicle fixation 2 and the intravertebral implant 1. The term partialsecuring denotes the locking of at least one degree of freedom betweenthese two parts. The pedicle fixation 2 then abuts on the shoulder 121.As such, the intravertebral implant 1 has an additional support point inthe pedicle. According to one embodiment, the vertebral implant 1 is notsecured to the pedicle fixation 2 by screwing. According to oneembodiment, the posterior part 12 of the intervertebral implant 1assembled with the pedicle fixation 2 does not traverse either side ofthe pedicle fixation 2. According to one embodiment, the posterior part12 of the vertebral implant 1 is mounted in the anterior inner portion23 of the pedicle fixation 2.

As represented in FIGS. 7A and 7B, the expansion of the intravertebralimplant 1 is performed by pulling on the central traction tube 13, bymeans of the tube 52 of the insertion instrument 5 (not shown in thefigures). The central traction tube 13 can slide unidirectionally in theposterior part 12 of the implant 1 so as to enable deployment whilepreventing removal. Pulling the central traction tube 13 enables thedeployment of the intervertebral implant 1 by moving the anterior andposterior ends of the anterior part 11 closer together. According to oneembodiment, the deployment makes it possible to separate the plates inthe vertebral body. This expansion in the vertebral body induces theanterior displacement of the implant: the anterior part 11 of theexpandable implant slides through the anterior inner portion 23 so thatthe anterior part 11 of the intervertebral implant is adapted optimallyto the environment wherein it is deployed. Advantageously, the slidinglink between the posterior inner portion 23 of the pedicle fixation 2and the posterior part 12 of the implant 1 is suitable for adapting theposition of the intervertebral implant 1 deployed in the vertebral bodyindependently of the position of the pedicle fixation 2.

As represented in FIG. 7B, the posterior part 12 can slide freely in ananterior inner portion 23, without however coming out thereof in orderto provide permanent additional support, so as not to constrain thedeployment of the intravertebral implant in a position dependent on thelocation of the pedicle fixation 2 in the pedicle. Indeed, the anteriorinner portion 23 is configured to lock the translations and rotations ofthe intervertebral implant 1 along the x and y axes of the pediclefixation 2, and enable the translation and rotation along the main axisof the pedicle fixation 2 (i.e. the z axis).

According to one embodiment, the dimensions of the posterior part 12 ofthe implant 1 are such that, once the posterior part 12 has beeninserted into the anterior inner portion 23, the implant 1 can no longerbe extracted from the pedicle fixation when it is implanted. Thelongitudinal dimension of the anterior inner portion 23 is sufficientlylong so that the posterior part 12 remains inserted and partiallysecured to said anterior inner portion 23 during deployment. Accordingto one embodiment, the length of the anterior inner portion 23 is indeedbetween 1 and 20 mm or between 5 and 15 mm.

According to this embodiment, the intravertebral implant 1 is free inaxial rotation and in anterior translation with respect to the pediclefixation 2. The deployment of the intravertebral implant 1 thus takesplace only on the basis of the intravertebral bone environment whichdetermines for the extendable anterior part 11 of the intervertebralimplant 1 the orientation and depth of deployment of said extendablepart. According to one embodiment, the intravertebral implant, andparticularly the posterior part 12 thereof, can be moved along one, two,three, four, five degrees of freedom, preferentially two degrees offreedom, more preferentially one degree of freedom in rotation and onedegree of freedom in translation, in the anterior inner portion 23.According to one embodiment, the intravertebral implant 1, andparticularly the posterior part 12 thereof, can move in rotation and intranslation along the z axis in the anterior inner portion 23.

According to one embodiment, after the expansion of the intravertebralimplant 1, the rotation and translation along z between theintravertebral implant and the pedicle fixation are locked, thussecuring the expandable intravertebral implant 1 to the pedicle fixation2.

According to one embodiment, the anterior part of the intravertebralimplant 11 is stabilised in the expansion position by injecting afilling material into the vertebra 4, via the at least one through hole131. The filling material is injected by means of an injector throughthe pedicle fixation 2, the cylindrical recess 122 of the posterior partof the implant 12 and the hollow traction tube 13, up to the anteriorpart 11 of the implant 1.

According to one embodiment, the posterior part of the intravertebralimplant 12 is secured to the pedicle fixation 2 by locking the relativemovements of the posterior portion 12 with respect to the pediclefixation 2 using securing means.

According to one embodiment, as illustrated in FIG. 8A, the posteriorpart of the intravertebral implant 12 is secured in the pedicle fixation2 by injecting a filling material. The filling material is injectedthrough the posterior inner portion 22 into the cylindrical recess 122and into the at least one through hole 124 so as to come into contactwith the inner surface of the anterior inner portion 23. Advantageously,the posterior portion 128 comprises a peripheral chamber 123 wherein theat least one through hole 124 opens. As such, the filling material fillsthe at least one through hole 124 and the peripheral chamber 123 inorder to distribute the filling material at the interface between theposterior portion 128 and the anterior inner portion 23 and thusincrease the contact surface area. In order to reinforce the securingfurther, the anterior inner portion 23 comprises at least one groove 231and the filling material injected into the cylindrical recess 122 fillsthe at least one through hole 124, the peripheral chamber 123 and the atleast one groove 231 of the anterior inner portion 23. Advantageously,the solidification of the filling material in the at least one axialgroove 231 reinforces the securing according to the degree of freedom inrotation about the z axis. Advantageously, the solidification of thefilling material in the at least one transverse groove 231 reinforcesthe securing according to the degree of freedom in translation along thez axis. Advantageously, the solidification of the filling material inthe at least one oblique groove 231 reinforces the securing along thedegrees of freedom in translation and rotation along the z axis.Advantageously, the solidification of the filling material in the atleast one groove 231 of non-constant cross-section reinforces thesecuring according to the degree of freedom in translation and rotationalong the z axis. According to one embodiment, the grooves 231 furtherenable the injection of the filling material to the anterior innerportion 23 reinforcing the securing further. According to oneembodiment, the filling material injected into the cylindrical recess122 fills the at least one through hole 124, the peripheral chamber 123and the at least one groove 231 of the anterior inner portion 23, andall or part of the volume of the anterior inner portion 23.Advantageously, the peripheral chamber 123 makes it possible to reachthe grooves 231 independently of the orientation of the intervertebralimplant 1, and particularly of the orientation of the posterior portion128, in the pedicle fixation 2.

According to one embodiment, as illustrated in FIG. 9A, the posteriorpart of the intravertebral implant 12 is secured in the pedicle fixation2 by means of a conical expansion cap 6. Said conical cap comprises anexternal thread and a flared posterior end. Said cap 6 is insertedthrough the posterior inner portion 22, optionally after injectingcement into the vertebra via the through hole 131, and targeted in theinternal thread 126 of the posterior portion 128. When the conical cap 6is screwed into the internal thread 126 of the posterior portion 128,the flared end of the cap abuts against the flared end of the posteriorportion 127 causing the radial deployment of the posterior portion,enabled by means of the slots 125. Advantageously, the radial deploymentof the posterior portion 128 in the anterior inner portion 23 securesthe posterior part of the intravertebral implant 12 in the pediclefixation 2 by pressing.

According to one embodiment, once the intravertebral implant 1 has beendeployed, secured to the pedicle fixation 2 and stabilised, if requiredby means of the injection of specially adapted bone cement orsubstitute, it is then possible to secure (i.e. connect) to the pediclefixation 2—intravertebral implant 1 assembly the posterior element 3 bymerely screwing and fastening same in the posterior inner portion 22 ofthe pedicle fixation 2. In this embodiment, the posterior element 3 isat least partially external to the vertebra 4 and is then capable ofreceiving posterior fixation elements such as rods or artificialligament systems or any other means for stabilising the vertebralfracture known to those skilled in the art.

The present invention also relates to a method for treating vertebralfractures comprising:

-   -   insertion of an implant system according to the invention        wherein the posterior part 12 is already inserted into the        anterior inner portion 23 in a vertebra 4 and screwing of the        pedicle fixation 2 in the vertebral pedicle by means of the        external thread 21;    -   expansion of the anterior part 11 of the intravertebral implant        1, particularly by pulling the central traction tube 13;    -   positioning of the anterior part 11 of the intravertebral        implant in the vertebral body enabled by the movement of the        posterior part 12 of the intravertebral implant 1 in translation        and rotation, along the main axis of the pedicle fixation 2, in        the anterior inner portion 23 of the pedicle fixation 2;    -   optionally, injection of a filling material into the vertebral        body via a through hole 131 to stabilise the anterior part of        the intravertebral implant 11; and    -   optionally, securing of the posterior part 12 in the anterior        inner portion 23.

The invention claimed is:
 1. An expandable intravertebral implant systemcomprising: an intravertebral implant comprising an expandable anteriorpart, and a posterior part coupled to the expandable anterior part,wherein the expandable anterior part and the posterior part areconfigured to be positioned within a vertebral body; and a pediclefixation configured to be anchored to a vertebral pedicle of thevertebral body to position the expandable anterior part and theposterior part within the vertebral body, the pedicle fixationcomprising a posterior inner portion and an anterior inner portiondefining a hollow portion for receiving the posterior part of theintravertebral implant such that the expandable anterior part isconfigured to move along at least two degrees of freedom relative to thepedicle fixation with the pedicle fixation anchored to the vertebralpedicle, and wherein movement of the posterior part in a first degree offreedom of the two degrees of freedom is independent from movement ofthe posterior part in a second degree of freedom of the two degrees offreedom.
 2. The expandable intravertebral implant system according toclaim 1, wherein the pedicle fixation comprises an external threadensuring the anchoring of said pedicle fixation in the vertebralpedicle.
 3. The expandable intravertebral implant system according toclaim 1, wherein the pedicle fixation comprises a main axis, and whereinthe posterior part of the intravertebral implant is configured to movein translation and in rotation along the main axis of the pediclefixation in such a way that the direction of expansion of the expandableanterior part of the intravertebral implant is independent from aposition of the pedicle fixation in the vertebral pedicle.
 4. Theexpandable intravertebral implant system according to claim 1, whereinthe expandable anterior part of the intravertebral implant comprises afirst and second plates, configured to respectively form first andsecond bearing surfaces in the vertebral body, the two surfaces beingsuitable for being separated from one another along a predefinedexpansion plane.
 5. The expandable intravertebral implant systemaccording to claim 1, wherein the anterior inner portion comprises atleast one groove on an inner surface thereof.
 6. The expandableintravertebral implant system according to claim 1, wherein theposterior part of the intravertebral implant defines a cylindricalrecess and at least one securing means suitable for locking in rotationand in translation the relative movements between the intravertebralimplant and the pedicle fixation.
 7. The expandable intravertebralimplant system according to claim 1, wherein the posterior part of theintravertebral implant defines a cylindrical recess and at least onesecuring means suitable for locking in rotation and in translation therelative movements between the intravertebral implant and the pediclefixation, and wherein the securing means comprises at least one throughhole passing through the posterior part from the cylindrical recess to aperipheral chamber of the posterior inner portion.
 8. The expandableintravertebral implant system according to claim 1, wherein theposterior part of the intravertebral implant defines a cylindricalrecess and at least one securing means suitable for locking in rotationand in translation the relative movements between the intravertebralimplant and the pedicle fixation, and wherein the securing meanscomprises at least two slots extending axially along the posterior innerportion, an internal thread, and a flared posterior end suitable forengaging with a conical expansion cap.
 9. The expandable intravertebralimplant system according to claim 1, further comprising a posteriorelement secured to the pedicle fixation and configured to be positionedpartially external to the vertebral body.
 10. The expandableintravertebral implant system according to claim 9, wherein theposterior element is secured to the pedicle fixation by means of athreaded rod screwed into an internal thread of the posterior innerportion.
 11. The expandable intravertebral implant system according toclaim 9, wherein the posterior element comprises a posterior portionsuitable for assembly with additional posterior fixation elements. 12.An expandable intravertebral implant system comprising: anintravertebral implant comprising an expandable anterior part configuredto be positioned within a vertebral body, and a posterior part; apedicle fixation configured to be anchored to a vertebral pedicle of thevertebral body, the pedicle fixation comprising a posterior innerportion and an anterior inner portion coupled to the posterior part,wherein the pedicle fixation comprises a main axis and wherein theposterior part of the intravertebral implant is configured to move intranslation and in rotation along the main axis of the pedicle fixationrelative to the anterior inner portion of the pedicle fixation in such away that the direction of expansion of the expandable anterior part ofthe intravertebral implant is independent from a position of the pediclefixation in the vertebral pedicle.
 13. The expandable intravertebralimplant system according to claim 12, further comprising an expansiontube traversing at least a length of the posterior inner portion andconnected to the posterior part of the intravertebral implant with theexpansion tube configured to retain the direction of expansion of theexpandable anterior part of the intravertebral implant independent fromthe position of the pedicle fixation.
 14. The expandable intravertebralimplant system according to claim 13, further comprising a workingcannula rotatably secured to the pedicle fixation with the expansiontube extends through the working cannula, wherein rotation of theworking cannula is independent of rotation of the expansion tube. 15.The expandable intravertebral implant system according to claim 13,further comprising a traction tube coupled to the intravertebral implantfor controlling deployment of the expandable anterior part, wherein theexpansion tube is coupled to the traction tube for actuating thetraction tube through a pulling input.
 16. The expandable intravertebralimplant system according to claim 12, further comprising an expansioncap configured to be inserted within the posterior inner portion tofacilitate radial deployment of the posterior inner portion intoengagement with the posterior part of the intravertebral implant. 17.The expandable intravertebral implant system according to claim 12,further comprising an expansion tube traversing at least a length of theposterior inner portion and connected to the posterior part of theintravertebral implant with the expansion tube configured to retain thedirection of expansion of the expandable anterior part of theintravertebral implant independent from the position of the pediclefixation.
 18. An expandable intravertebral implant system comprising: anintravertebral implant comprising an expandable anterior part, and aposterior part coupled to the expandable anterior part, wherein theexpandable anterior part and the posterior part are configured to bepositioned within a vertebral body; and a pedicle fixation configured tobe anchored to a vertebral pedicle of the vertebral body, the pediclefixation comprising a posterior inner portion and an anterior innerportion defining a hollow portion for receiving the posterior part,wherein the posterior part of the intravertebral implant is configuredto translate within the hollow portion of the pedicle fixation along amain axis of the pedicle fixation without requiring rotation of theintravertebral implant in such a way that a position of theintravertebral implant within the vertebral body is independent from aposition of the pedicle fixation in the vertebral pedicle.
 19. Theexpandable intravertebral implant system according to claim 18, whereinthe anterior inner portion and the intravertebral implant are notthreadably engaged.
 20. The expandable intravertebral implant systemaccording to claim 18, wherein the anterior inner portion comprises atleast one groove on an inner surface thereof.